1. Field of the Invention
This invention relates to an apparatus for the preparation of samples to be used for inspecting or observing a specimen isolated on a filter and sprayed with reagent by spraying a reagent on to a filer on which specimen has been isolated.
And further, the present invention relates to an apparatus for the production of samples to be used in order to measure the number of microorganisms present in the water, raw materials, semi-processed goods and other products used in the food, pharmaceutical, cosmetics, electronics and other industries, and more particularly, to a spraying apparatus for preparing samples by spraying an extractant and/or a reagent onto a filter on which the microorganisms have been isolated.
2. Description of the Related Art
Preparation of samples is performed by isolating a specimen on a filer and spraying reagent onto a filter on which the specimen is isolated when the interaction or reaction between the specimens and a reagent is observed or when the number of the isolated specimens is measured.
For example, in the food and beverage industries, as well as the cosmetics and electronics industries, the need to measure the level of microorganisms present during the production process and in the finished product is critical. Conventionally, such so-called plate counts have been performed using the agar plate method. However, in recent years a faster means of obtaining the plate count has been sought, leading to the development and use of apparatuses that skillfully combine membrane filtration, bioluminescence technology and weak-light spots detection techniques.
Apparatuses like that described above typically operate in the following manner: A specimen is filtered by and isolated on a membrane filter. The specimen is then sprayed with an extractant and then a luminescent reagent. A highly sensitive system then counts the number of luminescent bright spots, from which the plate count is derived. So-called rapid microorganism detection systems (RMDS) employing the method described above to determine the amount of microorganisms present in a specimen are currently on the market and presently being used, and are faster than the conventional agar plate method.
Generally, these RMDS operate by filtering and isolating an appropriate amount of microorganisms on a filter according to whether the specimen is to be diluted or is to be used in bulk. At that time the microorganisms are dispersed across the surface of the filter by holding the filter as level as possible. The microorganisms so isolated are the processed and transpired with alcohol or a variety of organic solvents used in the smallest possible amounts to extract the adenosine triphosphate (ATP) an so fix the ATP at or near the positions at which the host microorganisms have been isolated. If a solution containing a luminescent reagent composed of luciferin and the luminescent enzyme luciferase is then supplied the action of normally co-existent magnesium and ambient enzymes give off light. As with the solvents these reagents too, are used in the smallest possible amounts so that, by transpiration of the luminescent reagent solvent the luminescent points remain at or near the isolate microorganisms. The number of microorganisms present can then be calculated by counting the number of luminescent points. For those microorganisms from which the amount of ATP extracted from the microorganism is small and the luminescent points are indistinct the amount of ATP extracted is boosted by a short period of culturing in an a agar culture medium after dispersal and isolation on the filter.
Nevertheless, these RMDS are not free of problems. Specifically, these systems require that the membrane filter on which the sample is isolated be supported by a supporting means such as a carrier, the membrane filter sprayed with an adenosine triphosphate (ATP) extractant and a luminescent reagent and then positioned at a detector. In order to obtain a plate count efficiently, these systems must use the smallest possibile amount of ATP extractant and luminescent reagent applied simply, accurately and quickly. That is, applying more than the required amount of ATP extraction fluid either dilutes any ATP extracted or causes the extracted ATP to disperse widely, resulting in poor lighting and/or blockage of luminescence by the residual extractant.
In order to avoid or eliminate these problems substantial time and effort must be spent on the delivery of the extractant to the sample. In this respect similar problems also attend the delivery of the luminescent reagent, with the added consideration that the luminescent reagent used herein is not easy to obtain. As a result, it is commercially vital that only the minimum effective amount of luminescent reagent be used. Accordingly, the development of a sample preparation apparatus capable of accurately and efficiently delivering only these minimum effective amounts of extractant and luminescent reagent is desirable.
Separately, the preparation of the sample also require many steps, all of which it is desirable to automate to the extent possible. Up to now efforts have been made to automate portions of the sample preparation process though so far with only limited success. In particular, the movement of the filter between steps and the replacement of the filter itself require considerable skill and leave room for improvement. For example, the first drying, extraction processing, second drying and luminescent reagent processing are all steps which must be performed manually. Accordingly, processing a large volume of samples requires a great deal of time, which time also varies with the level of skill of the operator. Additionally, the filter may be contaminated by human hands during transport of the carrier or even dropped, thereby impairing the accuracy of the measurement. When conducting inspections prior to shipping food, for example, a delay in measurement can delay the entire shipment.
Additionally, the luminescent reagent spray apparatus used in the process of preparing a sample using the sample preparation apparatus must constantly be kept clean and free of contamination, and therefore it is necessary that the apparatus have a structure that allows easy cleaning of the cylinder that composes the spraying apparatus.
Additionally, the luminescent reagent to be sprayed must constantly be kept at a low temperature in order to maintain its effectiveness, and accordingly, the reagent container is usually covered by a cooling device. However, such an arrangement poses the problem of making it impossible to tell how much reagent remains available. Moreover, although it is desirable that human intervention in the preparation of the sample be kept to a minimum and that the process therefore be automated to the extent possible, it is still necessary, for example, to accurately gauge the state of the reagent spray during delivery to the sample.